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Dive Tables and Equivalent Air Depth

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1 Dive Tables and Equivalent Air Depth

2 Introduction Recommended Nitrox Dive Tables
Equivalent Air Depth metres sea water (msw) Use of EAD & Tables Air Tables & computers Nitrox computers

3 Nitrox Tables Buehlmann Tables Definitions Use – as air tables
Specific Nitrox Tables: EAN28 EAN32 EAN36 EAN40 See Appendix 2

4 Nitrox Tables Extra Rule Longer RNT
when moving from one mix to another the RNT is calculated using the table of new mix to be used Longer RNT Rule applies from any mix (EANx or air) to any other mix (EANx or air)

5 Equivalent Air Depth Nitrox – ppO2 > ppO2 Air
Nitrox –ppN2 < ppN2 Air Depth where EAN ppN2 equivalent to air Depth where ppN2 of Nitrox = ppN2 of Air Known as EAD

6 EAD - example Example: EAN36: ppN2 = 0.64 bar At 25m = 3.5 Bar (absolute) x 0.64 = 2.24 bar ppN2 Air: ppN2 = 0.79 bar Depth using air at which ppN2 = 2.24 bar 2.24 / 0.79 = 2.83 Bar or 18.3m The equivalent air depth using EAN36 at 25m is 18.3m

7 EAD Used for any mix Given depth Determine no-stop times
EAD 18.3m - use air tables Calculated in two ways: Use EAD formula Use EAD table (Appendix 3)

8 EAD Formula EAD (Bar) = FN2 in mix x P / 0.79 (FN2 in air) FN2 = decimal fraction of nitrogen P = pressure of dive (absolute) EAD in bar – convert to metres for equivalent depth in msw

9 Example: Using Nitrox 32% at 33 metres. Go across to reach 32%
Example: Using Nitrox 32% at 33 metres. Go across to reach 32%. Go down to 33 metres. Follow the row across to the left, where the E.A.D. can be read: 27 metres.

10 Using EAD and Air Tables
Use EAD with any Buehlmann Air table Determine no-stop time Care not to exceed depth Used for repetitive dives Keep within no-stop times Extra benefit of nitrox over air on safety stop

11 Air Tables & Computers Nitrox mix with standard tables or computer
Advantage Reduces risk DCI MOD (max ppO2 1.4) CNS% No-stop times

12 Nitrox Computers Use specific nitrox computer
Specify mix used prior to every dive Include in buddy check Track oxygen Track nitrogen CNS% No safety advantage Pre-selected % safety margin built in latest models Multi-level diving Always follow manufacturer’s recommendations

13 Summary Nitrox Dive Tables EAD concept and use
Air Tables and computers Nitrox computers Safer options Plan the dive and dive the plan

14 Questions?

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